|  | 5.3 | IP Routing Protocols
| 5.3.1 | Differentiating one routing protocol from the another
Routing is the process of determining where to send data packets destined for addresses outside the local network. Routers gather and maintain routing information to enable the transmission and receipt of such data packets. Routing information takes the form of entries in a routing table, with one entry for each identified route. Routing protocols allow a router to create and maintain routing tables dynamically and to adjust to network changes as they occur. Routing protocols can be differentiated from one another based on several key characteristics: First, the particular goals of the protocol designer affect the operation of the resulting routing protocol. Second, there are various types of routing protocols. Each protocol has a different effect on network and router resources. Third, as discussed earlier in this chapter, routing protocols use a variety of metrics to identify the best routes. Routing protocols are broadly divided into two classes: Interior Routing Protocols and Exterior Routing Protocols. Interior protocols are used for routing information within networks that are under a common network administration. All IP interior protocols must be specified with a list of associated networks before routing activities can begin. A routing process listens to updates from other routers on these networks and broadcasts its own routing information on those same networks. The interior protocols Cisco supports include RIP and IGRP. Exterior protocols are used to exchange routing information between networks that do not share a common administration. Exterior routing protocols include EGP and BGP. Exterior routing protocols require the following information before routing can begin: A list of neighbor routers (also called peers) with which to exchange routing information A list of networks to advertise as directly reachable
| Threaded Case Study
Washington Project: IGRP Design Goals Throughout the rest of the chapter, you will learn the concepts and configuration techniques to help address the following design goals for IGRP implementation in the Washington School District network: The network should use stable routing, and no routing loops should occur The network should quickly respond to changes in the network topology. The network should have low overhead, and IGRP itself should not use more bandwidth than is actually needed for its task. The network design should take into account error rates and level of traffic on different paths. .